darus67 wrote:Check out the venerable LM386 chip.There are a couple bazillion circuits found on google using this chip for basic audio amps.In its simplest form you can build an amp using about 4 components.

You might also look at Digi-key and just page through some of their selections. There are a whole new generation of audio amplifiers with similar simplicity, but added features such as de-pop circuitry and built-in mute functionality.

Radio Shack had the parts for that Amp circuit, so I breadboarded it tonight. I think I made a better radio than Amp.

My understanding is that 0.05uF caps are deprecated for 0.047uF, but I also substituted the 250uF electrolytic for a 220uF (that's all RS had), not sure of the impact of that.

Also, I used my Atari Punk Console as input and I'm not sure I have them connected correctly, just a single wire is going from the output of the APC to the input of the Amp. Should the grounds of the two circuits be connected somehow?

noise wrote:Also, I used my Atari Punk Console as input and I'm not sure I have them connected correctly, just a single wire is going from the output of the APC to the input of the Amp. Should the grounds of the two circuits be connected somehow?

Yes.

Yes yes yes yes YES.

Remember, all electrons want to travel a circular path- they leave some source, go out into the "world" (their local circuit), do some work (the amount of which is dictated by their voltage), then come home to the source at the end of their "day" (a couple of nanoseconds, really). Electrons are smart, though- if they can't see a way out of a circuit, they won't enter.

How do you have the two systems powered? Are both running on batteries? Wall warts? One of each? If you're using batteries for either half of the system, you definitely need to connect the grounds. Things get a little more complicated for wall warts, and there can be dangers inherent in connecting the grounds of two wall warts together depending on how they are manufactured.

I'm glad you asked these questions- it brings up another whole list of things I need to cover in my class.

uptownmaker wrote:How do you have the two systems powered? Are both running on batteries? Wall warts? One of each? If you're using batteries for either half of the system, you definitely need to connect the grounds. Things get a little more complicated for wall warts, and there can be dangers inherent in connecting the grounds of two wall warts together depending on how they are manufactured.

I'm glad you asked these questions- it brings up another whole list of things I need to cover in my class.

Each is powered by a 9V battery, so how would I connect the grounds, bridge the negative posts of the batteries?